From Chabad.org: The Levites, too, will not receive a share of the land of Israel. Instead they are entitled to a tenth of all the Israelites’ crops–this in return for the Tabernacle and Temple services which they render. Upon receiving this tithe, the Levites must, in turn, separate a tenth of this tithe and give it to the priests.
So the Levites get 10% of everyone’s crops, and they must give 10% of that to the priests. This underscores the importance of giving, regardless of how or how much you have. As Rav Dessler explains, giving is what makes us love others, not receiving. The more you “invest” in those around you by giving them love, food, money, attention or respect, the more you grow to appreciate and love them, and the phenomenon grows exponentially from there. But it all starts by giving (this is where I should link you do the Donate page for Lelamed.com, but I won’t).